76 
Mallophagan family Trimenoponidae 
the <$ genitalia and the special sensory organs of the first three abdominal 
segments which characterise that family. In addition it exhibits a fusion of 
prothorax and mesothorax, a condition not seen elsewhere in the Mallophaga. 
Trimenopon must rank as the type genus of a family Triinenoponidae. Philan- 
desia, which I have not had an opportunity to examine, probably belongs here 
also.” Vi 
While recognising the fact that this group is rather distinct from the other 
Menoponoid forms I am somewhat dubious as to its deserving family rank. 
However, before any very definite conclusions may be arrived at a thorough 
review of all the members of the Menoponoid group will be necessary. For 
the present I am accepting the family. I present the following statement of 
its characters. 
Menoponoid Mallophaga with abdominal stigmata present upon but five 
abdominal segments, the third to seventh; without a slit in the lateral margin 
of the head; without pharyngeal glands; with the antennae four-segmented; 
without combs or brushes of setae on the ventral side of the posterior femora 
or any of the abdominal sternites; with the mesonotum distinct or sometimes 
entirely fused with the pronotum, the pronotum usually strongly winged. 
As has been many times pointed out one of the most interesting problems 
in connection with the study of these ectoparasites is that of their distribution. 
This is, at least in part, the problem of the genetic relationships of their hosts. 
Just how far the two problems are concurrent is the most fascinating aspect 
of it all. In the case of the South American two-clawed species infesting 
mammals it is evident that the two problems diverge rather early, at least if 
we may form any conclusions from the rather scanty amount of information 
that is available. 
The majority of the two-clawed Mallophaga from mammals have been taken 
from marsupials in Australia and for these Harrison has named a distinct 
family the Boopidae. Two of the species herein dealt with are from marsupials, 
but apparently they find their nearest relatives not in the Australian marsupial- 
infesting species but in other species from South American rodents. The one 
consolation for those of us who like to see our theories work as they should 
is that these two species are apparently referable to the same genus. Of the 
other three species, one is from members of the rodent family Lagostomidae, 
one from the family Octodontidae and one from the family Caviidae. There 
is at least a suggestion that here the problem of the distribution of the parasites 
is in large part geographical. 
A similar situation appears to exist in the case of the Mallophagan family, 
Gyropidcie , the members of which occur upon mammals that appear to have 
little more in common than the circumstance that all are South American. ■ 
True, one species of this group has been described from a European rodent, 
but I am inclined to regard this record with grave suspicion. A rather extensive 
collection of Gyropids is available to me, and I hope in a later paper to consider 
this group at length. 
